gravity causes gradual contraction of nebular until near end when contraction speeds up and central star mass is formed
collapse causes spinning to occur and cloud rotates in one direction
flattened disk develops due to spinning so that whole mass is shaped like a disk with a lump in the center
planetsesimals collide with one another and begin the process
star enters t-tauri phase when H begins burning inside due to pressures at core; this causes heating and onset of solar wind

inner planets

planets made up of rocky bodies that are more dense and made of materials with higher melting temps

outer planets

gaseous bodies that are more similar to the nebular cloud in terms of composition(H and He) and are made of materials with low melting temps

stages of formation of inner planets

1. hadean event- early melting of the crust due to heating upon contraction of the earlier planet.
2. heavy bombardment- continued accretion of planestesimals in the form of meteors, asteroids, and small planets
3. post-heavy bombardment- develpment of a stable crust upon which oceans and ice sheets may for after an atmosphere develops around the planet

Differentiation of planets(earth)

heavy materials such as Fe and Ni sink towards the core
ligheter materials move to the crust(O, Si, Al, Ca)

iron cotastrophe

a viloent sinking event thought to have occurred on Earth when large quantities of Fe and Ni suddenly sank to the core about 4 billion years ago

Core

a body about 6,800 km across made mainly of Fe and Ni; temps= 5,000 celcius, solid in the interior part and liquid on the outer part
mostly metallic bonds

mantle

the bulk of the earths mass; a thick layer around the core consisting of minterals rich in O, Si, Mg, and Fe, much denser than crust; mostly ionic bonds

asthenosphere

a thin layer of rock under low enough pressure and high enough temperature to behave as a ductile material; ductile nature allows crustal plates to move upon it

crust

a thin layer or shell on the outer part of the Earth; lighter elements are concentrated here

big splash theory

while the earth was in the hadean stage a small planet struck it and was broken into smaller pieces. this orbiting material coalesced into the moon

moons unusual comp

there is no water in any lunar minerals and the minerals are more like Earths mantle than any other planet or satellite

size of moon

moon is very large, larger than mercury or pluto so it could have been formed as a former planet

moon has no core

the density of the moon is far to low for its size which means it does not have much of an iron core

impact basins

the large impact basins on the moon are only on one side. this is probably due to the orbital accretion of the moon in earths orbit.(basins only on earths side)

evidence of impact events on terrestrial planets

impact craters, rotation direction and axial tilt

impact craters

mercury venus mars and moon all have large impact craters, because there is no atemosphere they are not erroeded like earths. Also earth has a recycling crust

rotation direction and axial tilt

venus's rotation is opposite of all other planets thought to be from an impact. Earth's tilt is 23.5 tilt towards normal

global cloud bands that rapidly move along parallel lines of latitude
giant cloud spots or storms that persist between cloud bands for centuries; formed by shear between cloud bands moving at different speeds.

Galilean moons

Io- inner moon, most volcanically active planetary body in the solar system
Europa- 2nd moon, ice world with huge fissure cracks in the icy crust; may have a liquid ocean below the icre crust, most probable home of life outside earth in solar system
ganymede- the third moon from jupiter, and ice world with a possible ocean below the ice
callisto- the outer large moon of jupiter, an ice world that is the most heavily cratered body in the solar system.

other jovian moons

there are about thirty satellites of jupiter most of them captured asteroids or comets.

saturn moons

there are about 35 satellites of saturn
titan- a moon so large it is the size of mercury; a cloud shrouded, methane ice world with methane lakes and rivers. surface is covered with several meters of organic matter produced in the atemosphere.

saturns rings

bands of finely divided ice and rock that circle saturn in an equatorial band; debris in the rins range from 1mm to 10m long. rings are likely shattered satellites and are maintained in place by the gravity of smalle shepard moons.

other jovian rings

all jovian rings: all 4 jovian planets have ring systems but only saturns are visible from earth.

pluto

only planetary body of size in the solar system not visited at least once by a space craft from Earth
one sattelite that is almost the same size

asteroids

small rocky minor planets that orbit the sun; most occur in the belt between mars and jupiter in a region of the solar system where a planet did not form. Asteroids can collide and be pushed out into other orbits.

dinosaur

many think the dinosaurs probably were killed by an asteroid destroying them from an impact

comets

small rock bodies coated by ices which mainly dwell outside the solar system in the kuipler belt and oort cloud.

long period comets

come from the kuiper belt of oort cloud on orbits of 1000s of years in duration; most make one orbit of the sun and if they survive solar passage then never return.

short period comets

originally came from the kuiper belt or oort could but their orbits were changed by jupiter so that they are now in orbits of a few 10s to 100s years; they return periodically

meteroids

small fragments that orbit the sun

meteors

a meteroid that enters earth's atmosphere and burns up due to the heat caused bby entry. this causes a bright flash of light in the nigh sky.

meteorites

any piece of space debris that passes through earths atmosphere and impacts or lands on the surface

iron

made of interlocking nickel iron crystals

stony iron

made of interlocking nickel iron crystals embeded silicon

stony

made of silicone minerals

carbonaceous chondrites

contain silicate minterals with a large amount of organic carbon and peculiar round objects called chondrules and amino acids